Alarm-glass.



UNTTED %TA TE% EATENT @FFTQE HALZBERT K. HITCHCOCK, OF PITTSBUJRGH, PENNSYLVANIA, ASSIGNOR TO IPITTSBURGH PLATE GLASS COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANTA.

ALARM-Grass.

Specification of Letters Patent. Pateimtgdl Apr'. 24, 191%'.

Application filed March 30, 1915. Serial No. 18,127.

objects the provision of a window or sheet of glass of the character specified in which' Be it knownthat T, HALBERT K. HITCH- cooK, a. citizen of the United States, residing at Pittsburgh, in the countyV of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Alarm-Glass, of which the following is a specification. V

The invention relates to ;what may be termed alarm glass, that is glass which can not be cut or brokenwithout causing the actuation of a signal of some kind, such as a I bell. The glass is designed primarily for use in jewelers* windows and cases, but may be used in other relations where it is desired to guard a window' against unlawful entrance. vThe inventioIi has .for its primary a. very fine wire may be employed and which can be cheaply fabricated from ordinary y glass sheets, and the provision of a glass i larged section on the line TT of Fig. 1.

' curely attached to both sheets of glass, either 40 The transparent plate comprising my invention consists of a pair of glass Sheets 1 and 2, preferably plate glass, with an interposed tough resistant sheet or layer 3, preferably celluloid. The sheet 3 is /seby cementing or some other means, andcarries the signal wire 4: extending back and forth throughthe glass and connectedto an alarm mechanism (not shown) so constructed to give an alarm when the wire is broken.

This wire is preferably of very small` diameter so that it may be readily broken when the .window is fractured or cut. The compound plate is shown as supported in a window sash 5, but it will be understood that the glass is of general application. c

The Wire 4 may be embedded in the celluloid during the formation of thefcelluloid 'sheet or by placing it ,between two layers the art. I

which are subsequently cemented or welded together. Tn some cases this sheet may be made only thick enough to carry thewire, while in other` I cases, -where additional strength is desired this sheet may be made relatively thick. elluloid is preferred because of its strength, but in some' cases it may be desired to use a layer of 'some other material suc as balsam or of thin colorless cement of just sufiicient thickness to carry the wire.

It will be seen that the compound sheet constructed in accordance with my invention has certain advantages over constructions heretofore employed in which the signal wire was embeddedV in the glass itself, since such Sheets must be specially cast and the fine wire which it is desirable to use has a tendency to cut or burn off in the operation. The compound sheet is much stronger than a single sheet of glass because f the celluloid so that the windowl resists entrance eten after the inner and outer glass Sheets are shattered,`` thus preventing any quick entrance through the window and removal of merchandise from the space behind it. Ordinary glass can be used in the construction of the window and no cutting of its surface to receive the wire/is necessary such as would be the case if the interposed transparent layer carrying theywire were not 'employed Other ad/vantagesincident to the invention will be readily apparent to those skilled in Whatilf claim is`z- 1. Tn combination a compound alarm plate comprising two sheets of glass with an interposed transparent `layer of tough resistant material in which is embedded a signal wire extending back and forth through the layer.

2. Tn combination a compound alarm plate comprising two sh'eets of glass with'an interposed transparent layen of material attached to the Sheets, and in'which is embedded a. signal wire ext/ending back and forth through thelayer.

3. Tn combination a compound alarm plate comprising two sheets of glass with an 1nterposed'transparent layer'of celluloid` attached to the sheetsand in which isg'einfi' i bedded a signal wire extending back'f-'and' forth through the layer.

4. Tn combination a compound alarm/plate comprising a sheet of glass to one side of Which is attached a transparent sheet of tough resistant Vmaterial o ther than glass in which is embedded asignal Wire e xtending' back and forth through the sheet.

5." In combination a compound alarm plate comprising a sheet of glass to one side of Which is attached a transparent layer of insulating material "other .than glass having embedded therein a signal wire extending 10 'back and forth through the layer.

HALBERT K. HITCHCOCK. 

